DIN 41626 inserts.  Coaxial connectors used in conjunction with DIN 41612 mixed layout housings.  These inserts are suitable for use up to 1.5GHz

Important Note: Do not mix 50ohm and 75ohm variants of this series or damage will occur to the centre contacts.

For details; http://www.coax-connectors.com/products/connectors/41626-(din).aspx